MATERIAL. HANDLING—TRANSPORTATION OF SOLIDS 105
Net Operating Cost:
Example.—Required the net operating cost of a 500-ft. bucket carrier—lift, 150 ft.; horizontal travel, 350 ft.—handling 120,000 tons of fine coal per year. Carrier to be operated 1,500 hr. per year, with power delivered at carrier drive valued at 3 cts. per horsepower.
Required capacity of carrier (120,000 -f- 1,500)...... 80 tons per hour.
Advisable speed (Table 12)....................... 80 ft. per minute.
Fine coal weighing about 50 Ib. per cubic foot and the carrying capacity of a bucket carrier being proportional to its speed, a carrier capable of handling about 100 tons of material weighing 100 Ib. per cubic foot when run at a speed of 50 ft. per minute would be required. Select 24 by 20 in. buckets spaced 24 in. Table 13 Check:
4.28t0JZ X 80 X 50
8 100,000 X 24
wH = 11,215
As I = 24, w* = 467.3, w = 21.62 in. Select 24 by 24 in. buckets, spaced 24 in.
(28 X 350 + 108 X 150)80 , 9 X 80 - " - ~~
Formula (23)
Horsepower -
166^06
_ (103 X 350 + 133 X 150)80
Horsepower = ——
100,000
100
9_XJ*? 100
RCbc>
•• 28.4—say 30 hp. for pivoted buckets. Formula (24) = 52.0—say 55 hp. for rigid buckets. Formula (24)
RDbc
= 0.00208 X 24 X 24(150 + 350)50 + 0.005 X 24 X 24 X 350 + 15.25\/24 X 24 = 31,329—say 31,500 Formula (25)
= 0.00292 X 24 X 24(150 + 350)50 + (0.05 X 350 + 75)A/24 X 24 = 34,220—say 34,500 Formula (26)
= 0.0005 X 24 X 24 (150 + 350) 50 + 0.002 X 24 X 24 X 350 + 1.525 V24 X 24 = 7639.8—say 7,750 Formula (27)
= 0.00054 X 24 X 24(150 + 250)50 + (0.005 X 350 + 1.6) V24 X 24 « 7,856.4—say 7,900 Formula (28)
Take market price at 25 per cent above relative costs. Cost = 1.25 X 31,500 = $39,375.00—bucket carrier with rigid buckets. = 1.25 X 34,500 = $43,125.00—bucket carrier with pivoted buckets.
Rigid buckets Pivoted buckets
(0 085 X 39 375) $ 3,346 88
Fixed charges: $ 3,665 63
(0 06 X 24*X 1 500) 2,160.00
Labor charge : (0 05 X 24 X 1 500) 1,800 00
(0 015 X 55 X 1 500) 1,237.50
Supply expense (0 015 X 30 X 1 500) ..... 675 . 00
(0 03 X 55 X 1 500) ..... 2,475.00
Power charge : (0 03 X 30 X 1 500) ..... 1,350.00
Depreciation : (1.25 x 7,750 X^Q) ;;;;;;;; / 1500\ 5,812.50 5,925.00
(1.25 X 7,900X2555) "".... fltl K fiOl 00 <M q /TIC fiq